Sheathing for aeroplane propellers



'T. F. HAMILTON.

SHEATHING FOR AEROPLANE PROPELLERS.

APPLICATION FILED OCT-3|, I918.

Patented J an. 31, 1922.

INVENTOR rhomasflfiamdl'on ATTORNEYS.

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\ mnonss r. nAmIL'roN, or KILW AUKEE, WISCONSIN.

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To all whom it may concern Be it known that 1,.THOMAS Fos'rnn I'IAM- nzron, a. eitizenof the United States, and a resident of Milwaukee in the county of Milwaukee and State of isconsin, have invent ed certain new and useful Im roven entsrin *Sheathings for Aeroplane rofiellers, of

which the 'followin is a specification.

invention re ates to improvements in M airpiime propellers, and it consists in the and also whereby the accumulation of water Figure 1 is an elevation of a propeller i of Flgure 3, and $5 especially at the outer extremity of each blade tip is prevented.

Other objects and advantages will appear in the 'following specification, reference be inlgi Ihad to the accompanying drawing in w c blade, showing the customary form of sheathing,

Figure 2 is an elevation of the same blade, illustrating the application of the improved sheathing,

Figure 3 is a longitudinalsection on the line 2-2 of Figure 2,

Fi re 4 is a cross section on the line &4

Figure 5 is a. detail view illustrating the manner of fastening the sheathing plates together.

In order that the pn e of the invention may be more fully un erstood, the customary manner or sheathing the end of a pro peller blade is shown in Figure 1. Here the metallic sheathin leading edge of t e bla 2, by any suitable fastening means such as generally indicated at 3.

Thismetal sheath 1 is usually made of brass, copper or Monel metal and is intended to protect the tips of the propeller blades from water spray, sand and various foreign particles. Propellers that are driven by the modern high-power engines, invariably flex at the outer tips to a certain extent.

This flexure of the tips is unavoidable and in fact is to some extent desirable. It has been demonstrated in practice that a good portion of the propeller blade, including up Specification of Letters Patent.

- blade.

1 is 833311911 to the tip and.

Patented Jan 31, .1922.

Application filed October 31,1918. Serial No. 280,489.

proximatelytwo-thirds of the length of the leading edge, is subject to abuse by the elements It is to protect the propeller blades made use of.

fiv'vmg to the factthat the wood will flex and return'to its normal osition, .while the metal of the sheath will ex but will not return to its normal position, serious and dangerous vibrations are set up due to the buckling of the metal sheath under the cir cumstances' named above. The consequent fromsuch abuse, that the metal sheath is funbafanoing of the pro ller is furthered to a stil'lngreater degree y the aldniission of water between the sheath and propeller Now having the existing defects 'in sheathed propeller blade constructions in mind, attention is directed more particularly to the invention which is designed to overcome these defects.

In Figure 2, the improved sheathing consists of a luralit of plates 4. These are applied in t is over apping arrangement illus-' trated at a number of places at 5 in Figure 4. In Figure 2, the dotted line 6 indicates the outline of the sheathing on the cham her side of the blade. By comparing Figures 2 and 4, it will be observed that the sheathing on the plane side of the blade extends in a little farther than it does on the camher side.

'Thesheathing plates are'fastened together,

"fastening means such as rivets or screws 7.

It is to be observed in Figure 5 that the openings in the plate beneath the overlapping part of the companion plate, are made either larger in diameter as indicated in one instance at 8, or in the shape of a slot as indicated at 9.,

Even though the sheathing plates are fastened together as just described, and also fastened to the propeller blade by other means 10 intermediately of the plate joints, there is still room for movement of one plate with respect to the other by reason of the loose joints illustrated in Figure 5 The looseness of the joints as well as the inclination thereof as well illustrated in Figure 2, enables the throwing out of water as it seeks the outer periphery under the influence of centrifugal force. It is deemed an obvious modification, to make the joints in other shapes than shown, without thenccessity of making an illustration in the drawing.

wvooden blade in'all degrees of flexure, sufficient room for relative movement being fully provided.

It may be stated in conclusion ,that the invention may be applied ,to the propellersof'any type of air craft such'as' aeroplanes,

loons and any other type of land and water vehicles which maybe propelledby an'airscrew. l

' The customary manner of securing the fastenings 3 in Figure 1, is to solder the same in place. This same principle is applied in 'oining the laps at the periphery of the lade as at 5 in Figure 4; The la ped join-ts 5'are loose as alread explaine ,so as to 'ermit the freedom oi 'movement.

Whi e the construction and arrangement ofthe sheath is'that of aenerally preferred form, obviously mo I changes may be madewithout departing from the spirit of of the claims. j j

,I claim:-- 1. A propeller. blade, a lurality ofjs hea'th-r ing plates ap lied to t e tip and to the camber and the leading e 5e, the joints of the lates overlapping and ward the periphery of motion of the blade, said joints being sta gered on the respective sides of'the bla e, said plates having ification and p 7 ing plates ap lied to t the invention or the scope I i ane sides of the blade alongv isposed at an inc mationito-v ings in the concealed parts being made larger than the ones above; fastening means assing throu h the joints into the blade, olding the p ates together but enabling sli ht movement of the plates, and other fastening means for fastenin the plates to the blade.

2. A sheathing or, propeller blades comprising in oombmation a; plurality of relal'apping edges, 'saidplatesbein formed to receive the leading edge of t e propeller blade, and means for holding'dovvn the overlying ed es of said plates' 1 l 3. A s eathing. for propeller. blades comti'vely'short plates or sections having -over hydro-aeroplanes, flying boats, dirigible balprisingin' combination a pluralityof r'elatively short plates orseetions having-overlapping edges, said plates being formed to receive the leading edges of the propeller blade, and meansfor holapping'edgesof said plates while permitting ativemovement between the overlying an Underlyingedges! v a .4. 'A propeller blade, a plurality of sheathe tip and to the camber and p ane sides of the blade along the leading edge, the joints of .the plates overlapping, said plates having registering openingsat the joints, the openings in 'the concealed parts being made larger than the "ones above fastenin the joints into the b ades, ho ding the plates means assing through together but enabling slight movement of the plates, and other fastening means for fastoning the plates to the blade.

THos. F. HAMILTON.

ding down the over-' 

